具有温度补偿的燃气表环境温度影响测试装置设计

Research on testing devices of diaphragm gas meter's performance impacted by temperature

目的:设计燃气表环境温度影响测试装置,此装置不仅能测试环境温度变化和被测气体温度变化对燃气表性能的影响,还能对具有温度补偿的燃气表进行误差检定。方法:本装置采用换热装置及恒温箱实现介质与环境温度的变化,采用CFX软件优化蛇管换热器的盘绕螺距与直径。提出基于PID短时稳定传热的温度调节方法,降低气体温度波动。结果:通过CFX软件仿真获得了蛇管换热器的最优的盘绕螺距和直径,蛇管以螺距L=55 mm、直径D=200 mm盘绕时换热效果最优。采用PID短时稳定传热法控制恒温槽介质温度波动在±0.25℃内,可使换热器出口温度波动在±0.5℃内。结论:通过优化换热器几何尺寸和改进恒温槽温度控制方法,降低了换热装置和恒温箱带来的不确定度,使整体装置精度仍能达到0.5级。

Aims:The paper aims to design the device for testing temperature influence.This device can not only test the influence of ambient temperature changes and gas temperature changes on gas meter performance,but also carry out error verification for the gas meter with the temperature compensation function.Methods:The heat exchanger and the thermostat were used to realize the change of medium and environment temperatures.The CFX software was used to optimize the coil pitch and diameter of the coil heat exchanger.In addition,a temperature regulation method based on a PID short-term stable heat transfer was proposed to reduce gas temperature fluctuation.Results:The optimal coiling pitch and diameter of the coil tube heat exchanger were obtained by CFX software;and the optimal heat exchange effect was obtained when the coil tube pitch was L =55 mm and the diameter was D =200 mm.The PID short-term stable heat transfer method was used to control temperature fluctuations of medium in the plus or minus 0.25 ℃,which made heat exchanger outlet temperature fluctuations within the plus or minus 0.5 ℃.Conclusions:By optimizing the geometry size of the heat exchanger and improving the temperature control method of the constant temperature tank,the uncertainty caused by the heat exchanger and the constant temperature tank is reduced,so that the overall device accuracy can still reach 0.5 level.